AC3 + mp3 sound in Divx, but the mp3 plays too fast

I don't know if this belongs to the audio forum, but there's no muxing forum, so I post it here. I'm trying to encode Con Air with two audio tracks, one 5.1 AC3 384k, the other 112k mp3. I'm using the AC3 audio filters and Morgan Stream Switcher in MediaPlayer for playback. Everything works ok, the Divx 5 file with AC3 sound (first audio track) is playing perfectly, no problems. The other audio is also available and plays perfectly, only the movie speeds up to 27.2 fps instead of 25fps. Sounds like Con Air was taken over by a bunch of smurfs, if you know what I mean ;) Any ideas why the movie plays at 27.2fps when I choose the second audio track?

and (I'm still curious) ???

oops, sorry, I forgot to answer. I never had that problem before, neither with AC3 and Divx, nor with mp3 and Divx. Only the two-track AC3 and mp3 Divx file shows this problem in Mediaplayer 6.4 (not in BSPlayer) and only with the mp3 track. My soundcard is a Philips PSC706 Acoustic Edge and I'm using Win2K SP2. I think the problem is somewhere software-related. Media Player can't make full use of the AC3 decoder options while BSPlayer lets me choose from all of the 4-channel, 5.1 channel and SPDIF out options. So, probably WMP sets something else wrong as well (even it shows 48kHz for the audio track when it plays too fast)

oh dear, I just found out the file is still having a problem in BSPlayer. First, it seemed to play the mp3 track fine because the audio was in sync and the movie was playing at 25fps. Then, when I watched it for a while, the sound got horribly out of sync. If I fast forwarded to another scene, it was in sync but began slowly to run out of sync again. The problem in BSPlayer is, that it says the audio was 44.1kHz. So, something must have gone wrong in the interleaving process - WMP wants to play the audio at 48kHz, but then it is pitched and the video is running too fast. BSPlayer is running the video at 25fps, but the audio seems to be 44.1kHz at the same time and is running out of sync. I don't really get it... Maybe it's just very problematic to make an avi file with two audio tracks of which one is AC3 and the other is VBR mp3 (which is a possible problem for avi files anyways). So, I have given up the idea of having two audio tracks and I just add subtitles to the movie. Maybe I'll try again on another movie with CBR mp3 and AC3 :)

I just realized that BSPlayer seems to have a problem with VBR mp3 in general. The audio always starts to run out of sync, even with normal divx files with just one audio track.

Have you tried PowerDivX and Zoomplayer? If I have some time tonight I will make a movie with AC3 and CBR MP3, and report back.

I made a DivX4 with AC3 and MP3 (CBR and 44.1kHz). Both PowerDivX and Zoomplayer (although I didn't try the newest version) crached when opening the file. WMP played the AC3 stream, but when I switched to the MP3 stream (with Morgan Stream switcher) I heard only noise. Finally bsplayer did his job and stayed in sync. Sorry that I can't help you ...

PowerDivx "New Generation" doesn't seem to be new enough to like Divx5. It plays Divx 3.11 with CBR mp3, but it crashes on every other file I tried... I'm just about to try BSplayer with AC3 and CBR mp3, only I still struggle with the conversion because dynamic compression with Besweet (even light DC) seems to result in distorted sound with the German Con Air soundtrack. Well, I guess it wouldn't be fun if it was easy to do ;)

OK, I finally managed to make a Divx5 file with AC3 and MP3 (CBR, 48kHz) and experienced exactly the same as you did: "WMP played the AC3 stream, but when I switched to the MP3 stream (with Morgan Stream switcher) I heard only noise. Finally bsplayer did his job and stayed in sync." So, now we know that BSplayer only has a little sync problem with ABR and VBR mp3, but manages to play everything else. WMP plays ABR and VBR soundtracks right, but has a problem with two audio streams (at least in different formats, I guess 2xAC3 would be ok?). And finally, Powerdivx seems to have a big problem in general ;)

I tried it, but this file doesn't tell WMP to switch the audio codec, it only shows "English (VO)" and "Francais" instead of "Audio 1" and "Audio 2" on the selection menu. Then, I tried other codecs (maybe they wouldn't try to decode the 2nd audio stream and leave this to an mp3 codec - because that's why there is only noise, WMP assumes the 2nd stream is AC3 as well). Doesn't work with Ravisent or Cyberlink as well. The Odio Dekoda then only decodes the second audio, the first audio track is vanished from the menu. When the Odio Dekoda is also uninstalled, then the same happens with the default Fraunhofer mp3 codec - the first Audio (AC3) can't be decoded, but the second is running fine. So, the only solution for WMP to play this file seems to be: install AC3 codec for playback of the first track, uninstall all AC3 codecs for playback of the second track. I rather use BSPlayer, it's easier than this method :) P.S.: There's still one thing I don't get - why the hell was WMP able to switch the Audio codec to mp3 when I was trying this with a second audio track in ABR-mp3? I mean it was playing at a false framerate due to problems with ABR/VBR in a dual-audio avi, but at least it got the codec right. The only difference about the two mp3 is that this one now is CBR, it was also made using Besweet and Lame 3.92.